The invention relates to an air-actuated drive unit used to transmit rotative forces from an input shaft to a rotatably mounted output shaft. In particular, the invention provides for the conversion of a mechanically-actuated drive unit to an air-actuated drive unit especially in those circumstances where there is a limited amount of space available on the input drive shaft.
Typically, when an air-actuated drive unit, such as a brake or clutch, is provided for an input/output drive shaft combination, a rotary air shaft seal, such as the Power Flo model 700 manufactured by the Carlson Company, Incorporated of Wichita, Kans., is mounted on the input drive shaft to receive air from a stationary air supply source. A spider member adapted for mounting the air-actuated drive unit is also fixed on the input drive shaft separate from the air-shaft seal and rotates with the input drive shaft. A drive unit is actuated by air which is delivered from the air shaft seal via a conduit which is external to the input drive shaft. Upon actuation of the drive unit, the output shaft will rotate at a rate relative to the rate of rotation of the input drive shaft.
In certain applications there is not enough space on the input drive shaft to allow both the rotary air shaft seal and the spider member to be mounted on the shaft. In such an application, the usual way to provide air to the drive unit is to rifle drill an axial bore and then drill a connecting transverse bore in the input drive shaft which allow air from an air supply source to communicate with the drive unit via a rotary union connected to the input shaft. The rifle drilling procedure is time-consuming, and serves to reduce the integrity of the input drive shaft. In industrial applications where large industrial drive transmissions are involved, long down-times such as six weeks are required in order to rifle drill the input shaft for routing of a suitable air supply. Accordingly, it will be desirable to provide a means for delivery of actuating air to an air-actuating drive unit which would not require the drilling of the input drive shaft.
Certain devices have been patented, such as those shown in U.S. Pat. No. 2,823,777 and U.S. Pat. No. 3,796,514, which provide for the supplying of a pressurized fluid from a stationary supply source to a rotating drive unit. However, these devices do not lend themselves to industrial applications where the problem of connecting two rotatably mounted shafts typically exists. The devices are complicated in their structure and designed for specialized usages.
Accordingly, an object of the present invention is to provide an air-actuated drive unit suitable for industrial applications which receives air from a stationary air supply source and by means external to an input drive shaft.
Another object of the present invention is to provide an air-actuated drive unit having a spider member which can be mounted in connection with an air shaft seal adaptor on an output drive shaft in a limited amount of space.
Still another important object of the present invention is to provide a method for converting a mechanically-actuated drive unit to an air-actuated drive unit.
Still another important object of the present invention is to provide a method for allowing an air-actuated drive unit to be mounted in a compact space on an input drive shaft of limited length.